decoder.c

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/*
 * This file is part of the libsigrokdecode project.
 *
 * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
 * Copyright (C) 2012 Bert Vermeulen <bert@biot.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include "libsigrokdecode-internal.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
#include "libsigrokdecode.h"
#include <glib.h>

/**
 * @file
 *
 * Listing, loading, unloading, and handling protocol decoders.
 */

/**
 * @defgroup grp_decoder Protocol decoders
 *
 * Handling protocol decoders.
 *
 * @{
 */

/** @cond PRIVATE */

/* The list of loaded protocol decoders. */
static GSList *pd_list = NULL;

/* srd.c */
extern SRD_PRIV GSList *searchpaths;

/* session.c */
extern SRD_PRIV GSList *sessions;
extern SRD_PRIV int max_session_id;

/* module_sigrokdecode.c */
extern SRD_PRIV PyObject *mod_sigrokdecode;

/** @endcond */

static gboolean srd_check_init(void)
{
        if (max_session_id < 0) {
                srd_err("Library is not initialized.");
                return FALSE;
        } else
                return TRUE;
}

/**
 * Returns the list of loaded protocol decoders.
 *
 * This is a GSList of pointers to struct srd_decoder items.
 *
 * @return List of decoders, NULL if none are supported or loaded.
 *
 * @since 0.2.0
 */
SRD_API const GSList *srd_decoder_list(void)
{
        return pd_list;
}

/**
 * Get the decoder with the specified ID.
 *
 * @param id The ID string of the decoder to return.
 *
 * @return The decoder with the specified ID, or NULL if not found.
 *
 * @since 0.1.0
 */
SRD_API struct srd_decoder *srd_decoder_get_by_id(const char *id)
{
        GSList *l;
        struct srd_decoder *dec;

        for (l = pd_list; l; l = l->next) {
                dec = l->data;
                if (!strcmp(dec->id, id))
                        return dec;
        }

        return NULL;
}

static void channel_free(void *data)
{
        struct srd_channel *ch = data;

        if (!ch)
                return;

        g_free(ch->desc);
        g_free(ch->name);
        g_free(ch->id);
        g_free(ch);
}

static void variant_free(void *data)
{
        GVariant *var = data;

        if (!var)
                return;

        g_variant_unref(var);
}

static void annotation_row_free(void *data)
{
        struct srd_decoder_annotation_row *row = data;

        if (!row)
                return;

        g_slist_free(row->ann_classes);
        g_free(row->desc);
        g_free(row->id);
        g_free(row);
}

static void logic_output_channel_free(void *data)
{
        struct srd_decoder_logic_output_channel *logic_out_ch = data;

        if (!logic_out_ch)
                return;

        g_free(logic_out_ch->desc);
        g_free(logic_out_ch->id);
        g_free(logic_out_ch);
}

static void decoder_option_free(void *data)
{
        struct srd_decoder_option *opt = data;

        if (!opt)
                return;

        g_slist_free_full(opt->values, &variant_free);
        variant_free(opt->def);
        g_free(opt->desc);
        g_free(opt->id);
        g_free(opt);
}

static void decoder_free(struct srd_decoder *dec)
{
        PyGILState_STATE gstate;

        if (!dec)
                return;

        gstate = PyGILState_Ensure();
        Py_XDECREF(dec->py_dec);
        Py_XDECREF(dec->py_mod);
        PyGILState_Release(gstate);

        g_slist_free_full(dec->options, &decoder_option_free);
        g_slist_free_full(dec->binary, (GDestroyNotify)&g_strfreev);
        g_slist_free_full(dec->annotation_rows, &annotation_row_free);
        g_slist_free_full(dec->annotations, (GDestroyNotify)&g_strfreev);
        g_slist_free_full(dec->opt_channels, &channel_free);
        g_slist_free_full(dec->channels, &channel_free);

        g_slist_free_full(dec->outputs, g_free);
        g_slist_free_full(dec->inputs, g_free);
        g_slist_free_full(dec->tags, g_free);
        g_free(dec->license);
        g_free(dec->desc);
        g_free(dec->longname);
        g_free(dec->name);
        g_free(dec->id);

        g_free(dec);
}

static int get_channels(const struct srd_decoder *d, const char *attr,
                GSList **out_pdchl, int offset)
{
        PyObject *py_channellist, *py_entry;
        struct srd_channel *pdch;
        GSList *pdchl;
        ssize_t ch_idx;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        if (!PyObject_HasAttrString(d->py_dec, attr)) {
                /* No channels of this type specified. */
                PyGILState_Release(gstate);
                return SRD_OK;
        }

        pdchl = NULL;

        py_channellist = PyObject_GetAttrString(d->py_dec, attr);
        if (!py_channellist)
                goto except_out;

        if (!PyTuple_Check(py_channellist)) {
                srd_err("Protocol decoder %s %s attribute is not a tuple.",
                        d->name, attr);
                goto err_out;
        }

        ch_idx = PyTuple_Size(py_channellist);
        while (ch_idx--) {
                py_entry = PyTuple_GetItem(py_channellist, ch_idx);
                if (!py_entry)
                        goto except_out;

                if (!PyDict_Check(py_entry)) {
                        srd_err("Protocol decoder %s %s attribute is not "
                                "a list of dict elements.", d->name, attr);
                        goto err_out;
                }
                pdch = g_malloc(sizeof(struct srd_channel));
                /* Add to list right away so it doesn't get lost. */
                pdchl = g_slist_prepend(pdchl, pdch);

                if (py_dictitem_as_str(py_entry, "id", &pdch->id) != SRD_OK)
                        goto err_out;
                if (py_dictitem_as_str(py_entry, "name", &pdch->name) != SRD_OK)
                        goto err_out;
                if (py_dictitem_as_str(py_entry, "desc", &pdch->desc) != SRD_OK)
                        goto err_out;

                pdch->order = offset + ch_idx;
        }

        Py_DECREF(py_channellist);
        *out_pdchl = pdchl;

        PyGILState_Release(gstate);

        return SRD_OK;

except_out:
        srd_exception_catch("Failed to get %s list of %s decoder",
                        attr, d->name);

err_out:
        g_slist_free_full(pdchl, &channel_free);
        Py_XDECREF(py_channellist);
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

static int get_options(struct srd_decoder *d)
{
        PyObject *py_opts, *py_opt, *py_str, *py_values, *py_default, *py_item;
        GSList *options;
        struct srd_decoder_option *o;
        GVariant *gvar;
        ssize_t opt, val_idx;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        if (!PyObject_HasAttrString(d->py_dec, "options")) {
                /* No options, that's fine. */
                PyGILState_Release(gstate);
                return SRD_OK;
        }

        options = NULL;

        /* If present, options must be a tuple. */
        py_opts = PyObject_GetAttrString(d->py_dec, "options");
        if (!py_opts)
                goto except_out;

        if (!PyTuple_Check(py_opts)) {
                srd_err("Protocol decoder %s: options attribute is not "
                                "a tuple.", d->id);
                goto err_out;
        }

        for (opt = PyTuple_Size(py_opts) - 1; opt >= 0; opt--) {
                py_opt = PyTuple_GetItem(py_opts, opt);
                if (!py_opt)
                        goto except_out;

                if (!PyDict_Check(py_opt)) {
                        srd_err("Protocol decoder %s options: each option "
                                        "must consist of a dictionary.", d->name);
                        goto err_out;
                }

                o = g_malloc0(sizeof(struct srd_decoder_option));
                /* Add to list right away so it doesn't get lost. */
                options = g_slist_prepend(options, o);

                py_str = PyDict_GetItemString(py_opt, "id");
                if (!py_str) {
                        srd_err("Protocol decoder %s option %zd has no ID.",
                                d->name, opt);
                        goto err_out;
                }
                if (py_str_as_str(py_str, &o->id) != SRD_OK)
                        goto err_out;

                py_str = PyDict_GetItemString(py_opt, "desc");
                if (py_str) {
                        if (py_str_as_str(py_str, &o->desc) != SRD_OK)
                                goto err_out;
                }

                py_default = PyDict_GetItemString(py_opt, "default");
                if (py_default) {
                        gvar = py_obj_to_variant(py_default);
                        if (!gvar) {
                                srd_err("Protocol decoder %s option 'default' has "
                                        "invalid default value.", d->name);
                                goto err_out;
                        }
                        o->def = g_variant_ref_sink(gvar);
                }

                py_values = PyDict_GetItemString(py_opt, "values");
                if (py_values) {
                        /*
                         * A default is required if a list of values is
                         * given, since it's used to verify their type.
                         */
                        if (!o->def) {
                                srd_err("No default for option '%s'.", o->id);
                                goto err_out;
                        }
                        if (!PyTuple_Check(py_values)) {
                                srd_err("Option '%s' values should be a tuple.", o->id);
                                goto err_out;
                        }

                        val_idx = PyTuple_Size(py_values);
                        while (val_idx--) {
                                py_item = PyTuple_GetItem(py_values, val_idx);
                                if (!py_item)
                                        goto except_out;

                                if (py_default && (Py_TYPE(py_default) != Py_TYPE(py_item))) {
                                        srd_err("All values for option '%s' must be "
                                                "of the same type as the default.",
                                                o->id);
                                        goto err_out;
                                }
                                gvar = py_obj_to_variant(py_item);
                                if (!gvar) {
                                        srd_err("Protocol decoder %s option 'values' "
                                                "contains invalid value.", d->name);
                                        goto err_out;
                                }
                                o->values = g_slist_prepend(o->values,
                                                g_variant_ref_sink(gvar));
                        }
                }
        }
        d->options = options;
        Py_DECREF(py_opts);
        PyGILState_Release(gstate);

        return SRD_OK;

except_out:
        srd_exception_catch("Failed to get %s decoder options", d->name);

err_out:
        g_slist_free_full(options, &decoder_option_free);
        Py_XDECREF(py_opts);
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

/* Convert annotation class attribute to GSList of char **. */
static int get_annotations(struct srd_decoder *dec, size_t *ret_count)
{
        PyObject *py_annlist, *py_ann;
        GSList *annotations;
        char **annpair;
        ssize_t ann_idx;
        PyGILState_STATE gstate;

        if (ret_count)
                *ret_count = 0;

        gstate = PyGILState_Ensure();

        if (!PyObject_HasAttrString(dec->py_dec, "annotations")) {
                PyGILState_Release(gstate);
                return SRD_OK;
        }

        annotations = NULL;

        py_annlist = PyObject_GetAttrString(dec->py_dec, "annotations");
        if (!py_annlist)
                goto except_out;

        if (!PyTuple_Check(py_annlist)) {
                srd_err("Protocol decoder %s annotations should be a tuple.",
                        dec->name);
                goto err_out;
        }

        ann_idx = PyTuple_Size(py_annlist);
        if (ret_count)
                *ret_count = ann_idx;
        while (ann_idx--) {
                py_ann = PyTuple_GetItem(py_annlist, ann_idx);
                if (!py_ann)
                        goto except_out;

                if (!PyTuple_Check(py_ann) || PyTuple_Size(py_ann) != 2) {
                        srd_err("Protocol decoder %s annotation %zd should be a tuple with two elements.",
                                dec->name, ann_idx + 1);
                        goto err_out;
                }
                if (py_strseq_to_char(py_ann, &annpair) != SRD_OK)
                        goto err_out;

                annotations = g_slist_prepend(annotations, annpair);
        }
        dec->annotations = annotations;
        Py_DECREF(py_annlist);
        PyGILState_Release(gstate);

        return SRD_OK;

except_out:
        srd_exception_catch("Failed to get %s decoder annotations", dec->name);

err_out:
        g_slist_free_full(annotations, (GDestroyNotify)&g_strfreev);
        Py_XDECREF(py_annlist);
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

/* Convert annotation_rows to GSList of 'struct srd_decoder_annotation_row'. */
static int get_annotation_rows(struct srd_decoder *dec, size_t cls_count)
{
        const char *py_member_name = "annotation_rows";

        PyObject *py_ann_rows, *py_ann_row, *py_ann_classes, *py_item;
        GSList *annotation_rows;
        struct srd_decoder_annotation_row *ann_row;
        ssize_t row_idx, item_idx;
        size_t class_idx;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        if (!PyObject_HasAttrString(dec->py_dec, py_member_name)) {
                PyGILState_Release(gstate);
                return SRD_OK;
        }

        annotation_rows = NULL;

        py_ann_rows = PyObject_GetAttrString(dec->py_dec, py_member_name);
        if (!py_ann_rows)
                goto except_out;

        if (!PyTuple_Check(py_ann_rows)) {
                srd_err("Protocol decoder %s %s must be a tuple.",
                        dec->name, py_member_name);
                goto err_out;
        }

        row_idx = PyTuple_Size(py_ann_rows);
        while (row_idx--) {
                py_ann_row = PyTuple_GetItem(py_ann_rows, row_idx);
                if (!py_ann_row)
                        goto except_out;

                if (!PyTuple_Check(py_ann_row) || PyTuple_Size(py_ann_row) != 3) {
                        srd_err("Protocol decoder %s %s must contain only tuples of 3 elements.",
                                dec->name, py_member_name);
                        goto err_out;
                }
                ann_row = g_malloc0(sizeof(struct srd_decoder_annotation_row));
                /* Add to list right away so it doesn't get lost. */
                annotation_rows = g_slist_prepend(annotation_rows, ann_row);

                py_item = PyTuple_GetItem(py_ann_row, 0);
                if (!py_item)
                        goto except_out;
                if (py_str_as_str(py_item, &ann_row->id) != SRD_OK)
                        goto err_out;

                py_item = PyTuple_GetItem(py_ann_row, 1);
                if (!py_item)
                        goto except_out;
                if (py_str_as_str(py_item, &ann_row->desc) != SRD_OK)
                        goto err_out;

                py_ann_classes = PyTuple_GetItem(py_ann_row, 2);
                if (!py_ann_classes)
                        goto except_out;

                if (!PyTuple_Check(py_ann_classes)) {
                        srd_err("Protocol decoder %s %s tuples must have a tuple of numbers as 3rd element.",
                                dec->name, py_member_name);
                        goto err_out;
                }

                item_idx = PyTuple_Size(py_ann_classes);
                while (item_idx--) {
                        py_item = PyTuple_GetItem(py_ann_classes, item_idx);
                        if (!py_item)
                                goto except_out;

                        if (!PyLong_Check(py_item)) {
                                srd_err("Protocol decoder %s annotation row class tuple must only contain numbers.",
                                        dec->name);
                                goto err_out;
                        }
                        class_idx = PyLong_AsSize_t(py_item);
                        if (PyErr_Occurred())
                                goto except_out;
                        if (class_idx >= cls_count) {
                                srd_err("Protocol decoder %s annotation row %zd references invalid class %zu.",
                                        dec->name, row_idx, class_idx);
                                goto err_out;
                        }

                        ann_row->ann_classes = g_slist_prepend(ann_row->ann_classes,
                                        GSIZE_TO_POINTER(class_idx));
                }
        }
        dec->annotation_rows = annotation_rows;
        Py_DECREF(py_ann_rows);
        PyGILState_Release(gstate);

        return SRD_OK;

except_out:
        srd_exception_catch("Failed to get %s decoder annotation rows",
                        dec->name);

err_out:
        g_slist_free_full(annotation_rows, &annotation_row_free);
        Py_XDECREF(py_ann_rows);
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

/* Convert binary classes to GSList of char **. */
static int get_binary_classes(struct srd_decoder *dec)
{
        PyObject *py_bin_classes, *py_bin_class;
        GSList *bin_classes;
        char **bin;
        ssize_t bin_idx;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        if (!PyObject_HasAttrString(dec->py_dec, "binary")) {
                PyGILState_Release(gstate);
                return SRD_OK;
        }

        bin_classes = NULL;

        py_bin_classes = PyObject_GetAttrString(dec->py_dec, "binary");
        if (!py_bin_classes)
                goto except_out;

        if (!PyTuple_Check(py_bin_classes)) {
                srd_err("Protocol decoder %s binary classes should "
                        "be a tuple.", dec->name);
                goto err_out;
        }

        bin_idx = PyTuple_Size(py_bin_classes);
        while (bin_idx--) {
                py_bin_class = PyTuple_GetItem(py_bin_classes, bin_idx);
                if (!py_bin_class)
                        goto except_out;

                if (!PyTuple_Check(py_bin_class)
                                || PyTuple_Size(py_bin_class) != 2) {
                        srd_err("Protocol decoder %s binary classes should "
                                "consist only of tuples of 2 elements.",
                                dec->name);
                        goto err_out;
                }
                if (py_strseq_to_char(py_bin_class, &bin) != SRD_OK)
                        goto err_out;

                bin_classes = g_slist_prepend(bin_classes, bin);
        }
        dec->binary = bin_classes;
        Py_DECREF(py_bin_classes);
        PyGILState_Release(gstate);

        return SRD_OK;

except_out:
        srd_exception_catch("Failed to get %s decoder binary classes",
                        dec->name);

err_out:
        g_slist_free_full(bin_classes, (GDestroyNotify)&g_strfreev);
        Py_XDECREF(py_bin_classes);
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

/* Convert logic_output_channels to GSList of 'struct srd_decoder_logic_output_channel'. */
static int get_logic_output_channels(struct srd_decoder *dec)
{
        PyObject *py_logic_out_chs, *py_logic_out_ch, *py_item;
        GSList *logic_out_chs;
        struct srd_decoder_logic_output_channel *logic_out_ch;
        ssize_t i;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        if (!PyObject_HasAttrString(dec->py_dec, "logic_output_channels")) {
                PyGILState_Release(gstate);
                return SRD_OK;
        }

        logic_out_chs = NULL;

        py_logic_out_chs = PyObject_GetAttrString(dec->py_dec, "logic_output_channels");
        if (!py_logic_out_chs)
                goto except_out;

        if (!PyTuple_Check(py_logic_out_chs)) {
                srd_err("Protocol decoder %s logic_output_channels "
                        "must be a tuple.", dec->name);
                goto err_out;
        }

        for (i = PyTuple_Size(py_logic_out_chs) - 1; i >= 0; i--) {
                py_logic_out_ch = PyTuple_GetItem(py_logic_out_chs, i);
                if (!py_logic_out_ch)
                        goto except_out;

                if (!PyTuple_Check(py_logic_out_ch) || PyTuple_Size(py_logic_out_ch) != 2) {
                        srd_err("Protocol decoder %s logic_output_channels "
                                "must contain only tuples of 2 elements.",
                                dec->name);
                        goto err_out;
                }
                logic_out_ch = g_malloc0(sizeof(*logic_out_ch));
                /* Add to list right away so it doesn't get lost. */
                logic_out_chs = g_slist_prepend(logic_out_chs, logic_out_ch);

                py_item = PyTuple_GetItem(py_logic_out_ch, 0);
                if (!py_item)
                        goto except_out;
                if (py_str_as_str(py_item, &logic_out_ch->id) != SRD_OK)
                        goto err_out;

                py_item = PyTuple_GetItem(py_logic_out_ch, 1);
                if (!py_item)
                        goto except_out;
                if (py_str_as_str(py_item, &logic_out_ch->desc) != SRD_OK)
                        goto err_out;
        }
        dec->logic_output_channels = logic_out_chs;
        Py_DECREF(py_logic_out_chs);
        PyGILState_Release(gstate);

        return SRD_OK;

except_out:
        srd_exception_catch("Failed to get %s decoder logic output channels",
                        dec->name);

err_out:
        g_slist_free_full(logic_out_chs, &logic_output_channel_free);
        Py_XDECREF(py_logic_out_chs);
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

/* Check whether the Decoder class defines the named method. */
static int check_method(PyObject *py_dec, const char *mod_name,
                const char *method_name)
{
        PyObject *py_method;
        int is_callable;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        py_method = PyObject_GetAttrString(py_dec, method_name);
        if (!py_method) {
                srd_exception_catch("Protocol decoder %s Decoder class "
                                "has no %s() method", mod_name, method_name);
                PyGILState_Release(gstate);
                return SRD_ERR_PYTHON;
        }

        is_callable = PyCallable_Check(py_method);
        Py_DECREF(py_method);

        PyGILState_Release(gstate);

        if (!is_callable) {
                srd_err("Protocol decoder %s Decoder class attribute '%s' "
                        "is not a method.", mod_name, method_name);
                return SRD_ERR_PYTHON;
        }

        return SRD_OK;
}

/**
 * Get the API version of the specified decoder.
 *
 * @param d The decoder to use. Must not be NULL.
 *
 * @return The API version of the decoder, or 0 upon errors.
 *
 * @private
 */
SRD_PRIV long srd_decoder_apiver(const struct srd_decoder *d)
{
        PyObject *py_apiver;
        long apiver;
        PyGILState_STATE gstate;

        if (!d)
                return 0;

        gstate = PyGILState_Ensure();

        py_apiver = PyObject_GetAttrString(d->py_dec, "api_version");
        apiver = (py_apiver && PyLong_Check(py_apiver))
                        ? PyLong_AsLong(py_apiver) : 0;
        Py_XDECREF(py_apiver);

        PyGILState_Release(gstate);

        return apiver;
}

static gboolean contains_duplicates(GSList *list)
{
        for (GSList *l1 = list; l1; l1 = l1->next) {
                for (GSList *l2 = l1->next; l2; l2 = l2->next)
                        if (!strcmp(l1->data, l2->data))
                                return TRUE;
        }

        return FALSE;
}

static gboolean contains_duplicate_ids(GSList *list1, GSList *list2)
{
        for (GSList *l1 = list1; l1; l1 = l1->next) {
                unsigned int cnt = 0;
                const char **s1 = l1->data;
                for (GSList *l2 = list2; l2; l2 = l2->next) {
                        const char **s2 = l2->data;
                        if (!strcmp(s1[0], s2[0]))
                                cnt++;
                        if ((list1 == list2) && cnt > 1)
                                return TRUE;
                        if ((list1 != list2) && cnt > 0)
                                return TRUE;
                }
        }

        return FALSE;
}

static gboolean contains_duplicate_row_ids(GSList *list1, GSList *list2)
{
        for (GSList *l1 = list1; l1; l1 = l1->next) {
                unsigned int cnt = 0;
                const struct srd_decoder_annotation_row *r1 = l1->data;
                for (GSList *l2 = list2; l2; l2 = l2->next) {
                        const struct srd_decoder_annotation_row *r2 = l2->data;
                        if (!strcmp(r1->id, r2->id))
                                cnt++;
                        if (cnt > 1)
                                return TRUE;
                }
        }

        return FALSE;
}

/**
 * Load a protocol decoder module into the embedded Python interpreter.
 *
 * @param module_name The module name to be loaded.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_decoder_load(const char *module_name)
{
        PyObject *py_basedec;
        struct srd_decoder *d;
        long apiver;
        int is_subclass;
        const char *fail_txt;
        PyGILState_STATE gstate;
        size_t ann_cls_count;

        if (!srd_check_init())
                return SRD_ERR;

        if (!module_name)
                return SRD_ERR_ARG;

        gstate = PyGILState_Ensure();

        if (PyDict_GetItemString(PyImport_GetModuleDict(), module_name)) {
                /* Module was already imported. */
                PyGILState_Release(gstate);
                return SRD_OK;
        }

        d = g_malloc0(sizeof(struct srd_decoder));
        fail_txt = NULL;

        d->py_mod = py_import_by_name(module_name);
        if (!d->py_mod) {
                fail_txt = "import by name failed";
                goto except_out;
        }

        if (!mod_sigrokdecode) {
                srd_err("sigrokdecode module not loaded.");
                fail_txt = "sigrokdecode(3) not loaded";
                goto err_out;
        }

        /* Get the 'Decoder' class as Python object. */
        d->py_dec = PyObject_GetAttrString(d->py_mod, "Decoder");
        if (!d->py_dec) {
                fail_txt = "no 'Decoder' attribute in imported module";
                goto except_out;
        }

        py_basedec = PyObject_GetAttrString(mod_sigrokdecode, "Decoder");
        if (!py_basedec) {
                fail_txt = "no 'Decoder' attribute in sigrokdecode(3)";
                goto except_out;
        }

        is_subclass = PyObject_IsSubclass(d->py_dec, py_basedec);
        Py_DECREF(py_basedec);

        if (!is_subclass) {
                srd_err("Decoder class in protocol decoder module %s is not "
                        "a subclass of sigrokdecode.Decoder.", module_name);
                fail_txt = "not a subclass of sigrokdecode.Decoder";
                goto err_out;
        }

        /*
         * Check that this decoder has the correct PD API version.
         * PDs of different API versions are incompatible and cannot work.
         */
        apiver = srd_decoder_apiver(d);
        if (apiver != 3) {
                srd_exception_catch("Only PD API version 3 is supported, "
                        "decoder %s has version %ld", module_name, apiver);
                fail_txt = "API version mismatch";
                goto err_out;
        }

        /* Check Decoder class for required methods. */

        if (check_method(d->py_dec, module_name, "reset") != SRD_OK) {
                fail_txt = "no 'reset()' method";
                goto err_out;
        }

        if (check_method(d->py_dec, module_name, "start") != SRD_OK) {
                fail_txt = "no 'start()' method";
                goto err_out;
        }

        if (check_method(d->py_dec, module_name, "decode") != SRD_OK) {
                fail_txt = "no 'decode()' method";
                goto err_out;
        }

        /* Store required fields in newly allocated strings. */
        if (py_attr_as_str(d->py_dec, "id", &(d->id)) != SRD_OK) {
                fail_txt = "no 'id' attribute";
                goto err_out;
        }

        if (py_attr_as_str(d->py_dec, "name", &(d->name)) != SRD_OK) {
                fail_txt = "no 'name' attribute";
                goto err_out;
        }

        if (py_attr_as_str(d->py_dec, "longname", &(d->longname)) != SRD_OK) {
                fail_txt = "no 'longname' attribute";
                goto err_out;
        }

        if (py_attr_as_str(d->py_dec, "desc", &(d->desc)) != SRD_OK) {
                fail_txt = "no 'desc' attribute";
                goto err_out;
        }

        if (py_attr_as_str(d->py_dec, "license", &(d->license)) != SRD_OK) {
                fail_txt = "no 'license' attribute";
                goto err_out;
        }

        if (py_attr_as_strlist(d->py_dec, "inputs", &(d->inputs)) != SRD_OK) {
                fail_txt = "missing or malformed 'inputs' attribute";
                goto err_out;
        }

        if (py_attr_as_strlist(d->py_dec, "outputs", &(d->outputs)) != SRD_OK) {
                fail_txt = "missing or malformed 'outputs' attribute";
                goto err_out;
        }

        if (py_attr_as_strlist(d->py_dec, "tags", &(d->tags)) != SRD_OK) {
                fail_txt = "missing or malformed 'tags' attribute";
                goto err_out;
        }

        /* All options and their default values. */
        if (get_options(d) != SRD_OK) {
                fail_txt = "cannot get options";
                goto err_out;
        }

        /* Check and import required channels. */
        if (get_channels(d, "channels", &d->channels, 0) != SRD_OK) {
                fail_txt = "cannot get channels";
                goto err_out;
        }

        /* Check and import optional channels. */
        if (get_channels(d, "optional_channels", &d->opt_channels,
                                g_slist_length(d->channels)) != SRD_OK) {
                fail_txt = "cannot get optional channels";
                goto err_out;
        }

        if (get_annotations(d, &ann_cls_count) != SRD_OK) {
                fail_txt = "cannot get annotations";
                goto err_out;
        }

        if (get_annotation_rows(d, ann_cls_count) != SRD_OK) {
                fail_txt = "cannot get annotation rows";
                goto err_out;
        }

        if (get_binary_classes(d) != SRD_OK) {
                fail_txt = "cannot get binary classes";
                goto err_out;
        }

        if (contains_duplicates(d->inputs)) {
                fail_txt = "duplicate input IDs";
                goto err_out;
        }

        if (contains_duplicates(d->outputs)) {
                fail_txt = "duplicate output IDs";
                goto err_out;
        }

        if (contains_duplicates(d->tags)) {
                fail_txt = "duplicate tags";
                goto err_out;
        }

        if (contains_duplicate_ids(d->channels, d->channels)) {
                fail_txt = "duplicate channel IDs";
                goto err_out;
        }

        if (contains_duplicate_ids(d->opt_channels, d->opt_channels)) {
                fail_txt = "duplicate optional channel IDs";
                goto err_out;
        }

        if (contains_duplicate_ids(d->channels, d->opt_channels)) {
                fail_txt = "channel and optional channel IDs contain duplicates";
                goto err_out;
        }

        if (contains_duplicate_ids(d->options, d->options)) {
                fail_txt = "duplicate option IDs";
                goto err_out;
        }

        if (contains_duplicate_ids(d->annotations, d->annotations)) {
                fail_txt = "duplicate annotation class IDs";
                goto err_out;
        }

        if (contains_duplicate_row_ids(d->annotation_rows, d->annotation_rows)) {
                fail_txt = "duplicate annotation row IDs";
                goto err_out;
        }

        if (contains_duplicate_ids(d->annotations, d->annotation_rows)) {
                fail_txt = "annotation class/row IDs contain duplicates";
                goto err_out;
        }

        if (contains_duplicate_ids(d->binary, d->binary)) {
                fail_txt = "duplicate binary class IDs";
                goto err_out;
        }

        if (get_logic_output_channels(d) != SRD_OK) {
                fail_txt = "cannot get logic output channels";
                goto err_out;
        }

        PyGILState_Release(gstate);

        /* Append it to the list of loaded decoders. */
        pd_list = g_slist_append(pd_list, d);

        return SRD_OK;

except_out:
        /* Don't show a message for the "common" directory, it's not a PD. */
        if (strcmp(module_name, "common")) {
                srd_exception_catch("Failed to load decoder %s: %s",
                                    module_name, fail_txt);
        }
        fail_txt = NULL;

err_out:
        if (fail_txt)
                srd_err("Failed to load decoder %s: %s", module_name, fail_txt);
        decoder_free(d);
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

/**
 * Return a protocol decoder's docstring.
 *
 * @param dec The loaded protocol decoder. Must not be NULL.
 *
 * @return A newly allocated buffer containing the protocol decoder's
 *         documentation. The caller is responsible for free'ing the buffer.
 *
 * @since 0.1.0
 */
SRD_API char *srd_decoder_doc_get(const struct srd_decoder *dec)
{
        PyObject *py_str;
        char *doc;
        PyGILState_STATE gstate;

        if (!srd_check_init())
                return NULL;

        if (!dec || !dec->py_mod)
                return NULL;

        gstate = PyGILState_Ensure();

        if (!PyObject_HasAttrString(dec->py_mod, "__doc__"))
                goto err;

        if (!(py_str = PyObject_GetAttrString(dec->py_mod, "__doc__"))) {
                srd_exception_catch("Failed to get docstring");
                goto err;
        }

        doc = NULL;
        if (py_str != Py_None)
                py_str_as_str(py_str, &doc);
        Py_DECREF(py_str);

        PyGILState_Release(gstate);

        return doc;

err:
        PyGILState_Release(gstate);

        return NULL;
}

/**
 * Unload the specified protocol decoder.
 *
 * @param dec The struct srd_decoder to be unloaded.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_decoder_unload(struct srd_decoder *dec)
{
        struct srd_session *sess;
        GSList *l;

        if (!srd_check_init())
                return SRD_ERR;

        if (!dec)
                return SRD_ERR_ARG;

        /*
         * Since any instances of this decoder need to be released as well,
         * but they could be anywhere in the stack, just free the entire
         * stack. A frontend reloading a decoder thus has to restart all
         * instances, and rebuild the stack.
         */
        for (l = sessions; l; l = l->next) {
                sess = l->data;
                srd_inst_free_all(sess);
        }

        /* Remove the PD from the list of loaded decoders. */
        pd_list = g_slist_remove(pd_list, dec);

        decoder_free(dec);

        return SRD_OK;
}

static void srd_decoder_load_all_zip_path(char *zip_path)
{
        PyObject *zipimport_mod, *zipimporter_class, *zipimporter;
        PyObject *prefix_obj, *files, *key, *value, *set, *modname;
        Py_ssize_t pos = 0;
        char *prefix;
        size_t prefix_len;
        PyGILState_STATE gstate;

        set = files = prefix_obj = zipimporter = zipimporter_class = NULL;

        gstate = PyGILState_Ensure();

        zipimport_mod = py_import_by_name("zipimport");
        if (zipimport_mod == NULL)
                goto err_out;

        zipimporter_class = PyObject_GetAttrString(zipimport_mod, "zipimporter");
        if (zipimporter_class == NULL)
                goto err_out;

        zipimporter = PyObject_CallFunction(zipimporter_class, "s", zip_path);
        if (zipimporter == NULL)
                goto err_out;

        prefix_obj = PyObject_GetAttrString(zipimporter, "prefix");
        if (prefix_obj == NULL)
                goto err_out;

        files = PyObject_GetAttrString(zipimporter, "_files");
        if (files == NULL || !PyDict_Check(files))
                goto err_out;

        set = PySet_New(NULL);
        if (set == NULL)
                goto err_out;

        if (py_str_as_str(prefix_obj, &prefix) != SRD_OK)
                goto err_out;

        prefix_len = strlen(prefix);

        while (PyDict_Next(files, &pos, &key, &value)) {
                char *path, *slash;
                if (py_str_as_str(key, &path) == SRD_OK) {
                        if (strlen(path) > prefix_len
                                        && memcmp(path, prefix, prefix_len) == 0
                                        && (slash = strchr(path + prefix_len, '/'))) {

                                modname = PyUnicode_FromStringAndSize(path + prefix_len,
                                                        slash - (path + prefix_len));
                                if (modname == NULL) {
                                        PyErr_Clear();
                                } else {
                                        PySet_Add(set, modname);
                                        Py_DECREF(modname);
                                }
                        }
                        g_free(path);
                }
        }
        g_free(prefix);

        while ((modname = PySet_Pop(set))) {
                char *modname_str;
                if (py_str_as_str(modname, &modname_str) == SRD_OK) {
                        /* The directory name is the module name (e.g. "i2c"). */
                        srd_decoder_load(modname_str);
                        g_free(modname_str);
                }
                Py_DECREF(modname);
        }

err_out:
        Py_XDECREF(set);
        Py_XDECREF(files);
        Py_XDECREF(prefix_obj);
        Py_XDECREF(zipimporter);
        Py_XDECREF(zipimporter_class);
        Py_XDECREF(zipimport_mod);
        PyErr_Clear();
        PyGILState_Release(gstate);
}

static void srd_decoder_load_all_path(char *path)
{
        GDir *dir;
        const gchar *direntry;

        if (!(dir = g_dir_open(path, 0, NULL))) {
                /* Not really fatal. Try zipimport method too. */
                srd_decoder_load_all_zip_path(path);
                return;
        }

        /*
         * This ignores errors returned by srd_decoder_load(). That
         * function will have logged the cause, but in any case we
         * want to continue anyway.
         */
        while ((direntry = g_dir_read_name(dir)) != NULL) {
                /* The directory name is the module name (e.g. "i2c"). */
                srd_decoder_load(direntry);
        }
        g_dir_close(dir);
}

/**
 * Load all installed protocol decoders.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_decoder_load_all(void)
{
        GSList *l;

        if (!srd_check_init())
                return SRD_ERR;

        for (l = searchpaths; l; l = l->next)
                srd_decoder_load_all_path(l->data);

        return SRD_OK;
}

static void srd_decoder_unload_cb(void *arg, void *ignored)
{
        (void)ignored;

        srd_decoder_unload((struct srd_decoder *)arg);
}

/**
 * Unload all loaded protocol decoders.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.1.0
 */
SRD_API int srd_decoder_unload_all(void)
{
        g_slist_foreach(pd_list, srd_decoder_unload_cb, NULL);
        g_slist_free(pd_list);
        pd_list = NULL;

        return SRD_OK;
}

/** @} */